The first bald eaglets to be born on the north shore of Lake Ontario in decades have hatched near Hamilton.

The parents have been nesting at Cootes Paradise Nature Sanctuary at the Royal Botanical Gardens (RBG) for several years, but until now had not managed to hatch young.

These are thought to be the only eaglets to hatch in the region since bald eagle populations throughout North America collapsed in the 1980s, the RBG’s Head of Natural Lands, Tys Theysmeyer, told CBC News.

"We actually saw a little one poke its head up out of the nest," he said. "No one really knows when the last ones were born in this area. That's how long it has been."

The first eaglet was noted during monitoring of the nest site on March 22, with a second observed on March 23, said Theysmeyer. He said that it is still not known how many eggs are in the nest.

Theysmeyer started suspecting young ones were on the way when he noticed in mid-February that one of the birds was spending a considerable amount of time sitting on the nest. The nest has been monitored weekly from a nearby trail since, he said.

'Milestone' for the region

The eagles have nested at sites on both the north and south shores of Cootes Paradise marsh in Hamilton for several years, but failed to produce any young. Now that they have reached maturity, the eagles have become the first pair in decades to successfully nest on Lake Ontario’s northern shores, said Theysmeyer.

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A view from in the RBG eagle's nest in August of 2012. (supplied)

By the early 1980s, bald eagles were all but extinct in the northern Lake Ontario region. There were only four active nests in all of the Great Lakes, largely due to the widespread use of the pesticide DDT.

"This milestone is a testament to the restoration efforts of Project Paradise," Theysmeyer said.

"As we bring Cootes Paradise back to the condition it was in before the 20th century, species that once called this area their home will continue to return."

The nest, located in the Hopkins Woods Special Protection Area can be viewed at a safe distance, from the Marshwalk Boardwalk, accessed from the RBG Arboretum, the RBG said.